Chest wall fractures, and in particular, fractures of rib bones of the rib cage, may cause potentially life-threatening respiratory insufficiencies, accounting for up to 50% of the mortality in thorax injuries. Fractures of a rib bone may occur at any location along the bone. However, the most critical fractures often involve multiple fractures of each of a set of adjacent rib bones. In particular, if four or more consecutive rib bones of the rib cage each sustain two or more fractures, for example, to create a column of bone fragments flanked by fracture sites, the fracture pattern is referred to as a flail chest injury. In flail chest injury, a fractured region of the chest wall is detached from the remainder of the chest wall, and no longer held in position by the rib cage. Accordingly, this fractured region may move independently of the chest wall during respiration, resulting, for example, in insufficient ability for respiration.
Flail chest injury may be treated non-operatively or operatively to restore the anatomy and physiological function of the chest wall. Non-operative treatment generally involves aggressive pain control and mechanical ventilation. As a result, non-operative treatment has been associated with prolonged stays in the hospital and increased mortality rates. Operative treatment generally involves reducing and stabilizing rib fractures with surgical fixation devices (osteosynthesis hardware), such as metallic struts, plates or wires. Operative stabilization of flail chest injuries, such as with struts, plates, or wires, may provide significant benefits over non-operative treatment. For example, operative stabilization may reduce the need for, and thus the mortality associated with, prolonged mechanical ventilation. In addition, operative stabilization may dramatically reduce pain during respiration, yield faster fracture healing, prevent persistent respiratory compromise, and reduce cost for treatment.
As early as 1958, intramedullary pinning with stainless steel pins was introduced to stabilize rib fractures by inserting a thin plate in the intramedullary canal across the fracture site, see Moore, B.P., Operative stabilization of non-penetrating chest injuries, J. Thorac. Cardiovasc. Surg., 70, 619-639 (1975), the entire disclosure of which is hereby incorporated by reference. In other approaches, surgeons have inserted stainless steel (Kirschner) wires inside the ribs for rib fracture fixation. However, these thin, round wires provide little torsional stability, and may migrate over time.
In 1975, Paris et al. reported the use of stainless steel struts of three distinct sizes, which provided greater torsional stability, see Paris, F., et al., Surgical stabilization of traumatic flail chest, Thorax, 30, 521-527 (1975), the entire disclosure of which is hereby incorporated by reference. These struts were used either as an intramedullary nail inside a rib or as an external brace for application on a rib surface. For external bracing, such struts utilized a series of holes to accommodate strut fixation with suture wires.
Other fixation mechanisms have been utilized, such as the Judet plate and the Vecsei plate, but are configured exclusively for external fixation of rib fractures. In 1972, Rehbein plates were introduced, which combine internal and external fixation strategies, see Meier, P., et al., Zur Therapie des instabilen Thorax bei Rippenserienfrakturen, Schweiz. Med. Wschr., 108:606-613 (1978), the entire disclosure of which is hereby incorporated by reference. A Rehbein plate is a thin, straight, flexible plate, which is angled at the end that remains outside the bone. For insertion of a Rehbein plate, an access hole may be drilled through the outer cortex of a rib several centimeters in front of the fracture. Through this access hole, the Rehbein plate may be inserted into the intramedullary canal across the fracture site, until only the angled end section of the Rehbein plate remains outside the rib. The angled end section may be folded toward the rib surface and secured, if necessary, with suture wire. However, folding of the angled segment to the rib segment may decrease the strength of the plate at the folding line. Folding of the stainless steel plate after insertion in the rib may also cause undesirable high stress in the rib, which may lead to further fracture or splitting of the rib especially in elderly patients in which ribs are thin and fragile. Furthermore, suturing the plate end to the bone is time consuming and difficult. This is especially the case, when rib fractures are located in the rear portion of the rib where thick soft tissue and muscle layers over ribs complicate or prevent access.